Researchers at Washington University in St Louis have discovered a new way to measure oxygen in individual red blood cells in real time by using light and color, Bio Optics World reports.

The team of researchers, led by Lihong Wang, believes that this photoacoustic method, called photoacoustic flowoxigraphy, could be deployed for finding how oxygen reaches normal or diseased tissues of different organs and the extent to which disease therapies influence oxygen delivery in the body.

Red blood cells, or erythrocytes, are the organism's principal means of delivering oxygen to the body tissues via arteries, capillaries and veins. So far, the most common method for measuring oxygen in the blood has been a device called pulse oximeter. This method, however, only allows for monitoring oxygen levels in arteries, which means that it cannot determine the metabolism of oxygen, or the amount of oxygen being used by a person. The recent breakthrough provides for using light which gives the opportunity to see red blood cells squeezing through even tiny capillaries.

By emitting two differently-colored laser pulses at a red blood cell 20 µs apart, the researchers reached the same erythrocyte at almost the same location nearly simultaneously, receiving signals back at both colors, Wang explained. This method allowed the researchers to see the color of the red blood cell at any moment and how it changes in real time, making them able to determine the amount of oxygen delivered from each red blood cell over a specific period or distance. That way, they could specify the average oxygen delivery per unit length of capillary segment, Wang added.